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Discussion Starter · #1 ·
89 C2500 / 350tbi auto trans.
kind of inherited this truck from my son.
has 90K miles.
Been sitting for 2 years. put in new battery. fill gas tank.
Seemed good to go.

Check mileage on first tank, 12 mpg.
On the way home from the 2nd fill-up, started to cough, balk.
Limped in to the shop. was planning to have the tires balanced/rotated and brakes checked anyway. The brakes were soft and fluid was going somewhere. Diagnosed with bad fuel pump in the tank, rear brakes needed cylinders and rebuild. Recommended fuel pump, filter, plugs, wires, distributor cap, tune up.
I committed to the fuel pump and brakes...figured I could to spark plugs, wires, distributor cap.

So I got around to doing the plugs/wires/distributor cap today. Went for test drive. The check instrument light comes on, and the gauges peg out a couple of times. Transmission shifts hard between 1 and 2, then waits until you really wind it up to get 3rd. Stopped at my destination, popped the hood, smell rubber burning. oh-no. Couldn't see what was happening, so drove back home.

Start digging around and find a wire hanging loose on the drivers side touching the exhaust manifold. (found the smell) It has one of the push on spade type female ends, one wire in a small loom about 8 inches long. It branches out of a larger loom near the firewall. I didn't unplug it while changing the plugs/wires/distributor cap, so I have no idea where it goes. I pulled it off the exhaust manifold, which clears the instrument light problem. Haven't tried driving it again yet, so I don't know if the shifting problem is still there. Would like to know where to plug it back in...or is it some extra connection that I knocked loose while pulling plug wires?
 

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Discussion Starter · #4 ·
Figured out the wire....the PO installed a 'real' oil pressure gauge, left the original sensor wire dangling. I knocked it loose running the plug wires. The hard shifting is probably just normal and became more noticeable due to the power picked up with new plugs and the bottle of sea foam I poured into the gas tank. It gets 2nd at around 25 and third at around 45. If you bear down on it, it will go all the way to 53 or so for 3rd. Seems smoother if you are bearing down.
 
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